Recently, so-called electric-motor vehicles, such as environmentally benign electric automobiles, hybrid automobiles, and fuel-cell automobiles, have attracted attention. Saving energy by improving fuel consumption is preferable, from the viewpoint of friendliness to the environment. Improving fuel consumption by restricting the power performance of the vehicle or by restricting air-conditioning may sacrifice ease of operation of a vehicle and comfort in the interior space. Therefore, it is preferable to enable the driver to choose an option to save energy by means of a simple operation. To this end, the vehicle is provided with a switch or the like that issues a fuel-efficient running command to the control element thereof. This switch is also called “an eco-mode switch” or simply “an eco-switch.”
For example, Patent Document 1 discloses a control device of an electric automobile capable of switching between a normal mode and an economy mode. According to this control device, power consumption is saved by setting a torque command value of the running motor on the drive side in the economy mode to be 60% that in the normal mode. When the actual acceleration or required acceleration in the economy mode is 80% or less, hill-climbing torque is added, and when the actual acceleration or required acceleration is 90% or higher, hill-climbing torque is subtracted.
As a technique relevant to the invention, Patent Document 2 describes a vehicle transmission control device equipped with a plurality of drive sources. According to this control device, when the clutch is disengaged during gear-shifting, no drive force of the engine is transmitted and the driver feels a slowdown, and because of this a drive force is compensated for by an electric motor serving as a second drive source. In a case where the amount of reduction in compensating torque is greater than a predetermined reference torque, the control mode is switched to the rectangular wave control, because torque becomes insufficient when the control mode for the inverter is the normal sine wave control. This reference describes that the sine wave control achieves low vibration and low noise, but, at a modulation factor of 0.61, whereas the rectangular wave control can achieve high torque at a modulation factor of 0.78.
Patent Document 1: JP-A-10-248106
Patent Document 2: JP-A-2005-155862